Protein traps: using intracellular localization for cloning

A much-sought goal – the rapid cloning of genes whose protein products have specific intracellular localizations – has now been made possible. A visual screen of cells expressing fusions between coding DNA sequences and a reporter, such as green-fluorescent protein (GFP) or β-galactosidase, identifies cells with the pattern of interest. The DNA sequences encoding these targeted fusions can then be cloned either directly from these cells or by repeated rounds of screening and subdivision of library pools. It is expected that systematic screenings based on these methods will identify additional components for every compartment and define new domains, thus facilitating a more comprehensive understanding of the cellular architecture.